The invention relates to a conveying arrangement for processing printed products. The arrangement has an intake area where the printed products are fed to a conveying section, a plurality of deposit trays on which the printed products are transported along the conveying path and a delivery area at the end of the conveying path where the printed products are conveyed off.
During the processing, the printed products can be transported from one processing station to another with conveying arrangements of the aforementioned type. The printed products can be any type including, for example, perfect bound or thread-stitched book blocks, loose book stacks, loose sheets or brochures. In the processing stations, the printed products are stitched together, applied with glue or trimmed. For conventional perfect binding systems, conveying arrangements can supply to a trimming machine book blocks with glue applied to the spine. In the process of applying glue to the spine(s) of book blocks, loose sheet stacks can be bound together with heated adhesive (i.e., liquid glue) to form a magazine or book. The heated adhesive is then allowed to cool down or dry and harden considerably to reach a desired cutting firmness/consistency before the perfect-bound magazine or book can be moved to the next processing step, in particular to a side trimming station. To provide the required cooling time and/or drying time, the printed products in conventional perfect binding systems are transported with conveying belts over a specified cooling horizontal section after the binding operation. While on the cooling section, the adhesive hardens or cools down until it reaches the desired cutting or trimming firmness, wherein the cooling occurs at, for example, room temperatures.
Horizontal cooling sections can be several meters long, or even larger to ensure the necessary cooling time, and occupy large space. For that reason, cooling sections are often designed as towers to occupy considerably less space than horizontal cooling sections. The following designs are examples of conventional cooling towers.
In a first example of conventional cooling towers, the cooling section is a transport mat, on which the printed products are transported upward along a spiral path in a first tower and are subsequently transported downward along another spiral path in a second, adjacent tower. This is a comparatively space-saving design, but is disadvantageous in that much machine timing between different processing sections is lost and interferes with the further processing of the printed products.
In a second example of conventional cooling towers, a layer lift that operates on the basis of a so-called “paternoster principle” is used, wherein a specific number of deposit trays are arranged along a conveying arrangement and at least one printed product is placed onto each deposit tray. The printed products placed on deposit trays are initially conveyed upwardly and then downwardly. The machine timing is maintained with this type of operation. The disadvantage of this design is that, for a fast-running perfect binder, an extremely high tower of several meters in height, is required to gain the required cooling time. In addition, each deposit tray turns over at the top turning point and changes the orientation of the printed product. Such changes are undesirable in many cases.